A known cap in the related art is disclosed in, for example, Japanese Patent No. 3688373. As shown in FIGS. 29 and 30, the cap includes a main unit 203 attached to a mouth 202 of a double-walled container 201, a spout cylinder 204 provided on the main unit 203, a lid 205 for opening and closing the tip opening of the spout cylinder 204, an inner stopper 206 provided in the main unit 203 so as to be fit into the mouth 202, and a valve device 207 provided in the main unit 203.
The inner stopper 206 has a spout 208. The valve device 207 has a fitting portion 209, a disk portion 210, a disk discharge valve 211, and a suction valve. The discharge valve 211 opens and closes the spout 208. The discharge valve 211 is provided on the fitting portion 209 so as to vertically swing via a connecting portion 213. The suction valve is a valve for opening and closing a clearance between an air inlet port 214 and an air inlet passage 215.
The lid 205 contains a cylindrical inner ring 219 on an inner side thereof. When the lid 205 is closed, the inner ring 219 is fit into the tip opening of the spout cylinder 204 so as to seal the tip opening of the spout cylinder 204.
Thus, when a user opens the lid 205 and presses the double-walled container 201 with a hand, the suction valve is closed to act as a partition between the air inlet port 214 and the air inlet passage 215. This prevents air between an outer layer 216 and an inner layer 217 of the double-walled container 201 from being discharged and increases the internal pressure of the double-walled container 201. Thus, as indicated by a virtual line of FIG. 30 and in FIG. 31, the discharge valve 211 opens the spout 208, and then a fluid 218 in the double-walled container 201 is discharged from the spout cylinder 204 through the spout 208.
When the user releases pressure on the double-walled container 201, the internal pressure of the double-walled container 201 falls below an atmospheric pressure due to the restoring force of the outer layer 216 of the double-walled container 201. The discharge valve 211 then closes the spout 208 as indicated by a solid line of FIG. 30, a pressure between the outer layer 216 and the inner layer 217 of the double-walled container 201 falls below an atmospheric pressure, the suction valve is opened, and then air is fed between the outer layer 216 and the inner layer 217 from the air inlet port 214 through the air inlet passage 215.
In the related art, however, when a user presses the double-walled container 201, the discharge valve 211 quickly (concurrently with the press) opens the spout 208 as indicated by the virtual line of FIG. 30. Thus, as shown in FIG. 31, the fluid 218 in the double-walled container 201 may be rapidly discharged from the spout cylinder 204.
Moreover, when the user releases pressure on the double-walled container 201 and the discharge valve 211 closes the spout 208 as shown in FIG. 32, the fluid 218 may not fully return into the double-walled container 201 from the inside of the spout cylinder 204 through the spout 208. Unfortunately, it is difficult to reduce the amount of the fluid 218 remaining in the spout cylinder 204.
As has been discussed, if a large amount of the fluid 218 remains in the spout cylinder 204, when the lid 205 is closed to fit the inner ring 219 into the tip opening of the spout cylinder 204, the fluid 218 remaining in the spout cylinder 204 may leak out of the spout cylinder 204.
An object of the present invention is to provide a cap that allows sufficient time to discharge a fluid from a spout after a user presses a double-walled container, thereby preventing rapid discharge of the fluid from the spout.
Another object of the present invention is to provide a cap that can reduce the amount of fluid remaining in a spout cylinder when a user releases pressure on a double-walled container.